JP2011169233A - Variable nozzle structure of turbine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable nozzle structure of a turbine, having a simple structure, easy to manufacture and reduced in leakage of exhaust gas from a shroud side. <P>SOLUTION: The variable nozzle structure lies outside in the radial direction of a turbine impeller 2 in a turbine case 10 and includes a plurality of vanes 40 which are formed to be spanned between a shroud 3 and a hub 14 of the turbine case 10 with support shafts 41, 42 and are rotatably provided at intervals in the circumferential direction. Each vane 40 is provided with a support member 43 on a blade end face 45 on the shroud 3 side in close contact with at least a part of the blade end face 45. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a variable nozzle structure for a turbine.

  The variable nozzle of the turbine is located radially outside the turbine impeller in a turbocharger turbine case such as a turbocharger, and a plurality of vanes are arranged at intervals in the circumferential direction. The efficiency is improved by changing the angle of each vane according to the gas flow rate.

  In general, in the supercharger 1 provided with the variable nozzle 4, the exhaust gas discharged from the engine (not shown) is circumferentially moved in the scroll passage 12 of the turbine case 10 as shown in FIGS. Are distributed to the inlet of the turbine impeller 2, pass through the variable nozzles 4 composed of a plurality of vanes 40 arranged at intervals in the circumferential direction, and discharged from the exhaust port 13 while rotating the turbine impeller 2. As the turbine impeller 2 rotates, the rotating shaft 20 rotates, the compressor impeller (not shown) provided at the tip of the rotating shaft 20 also rotates, and the air guided from the outside to the compressor case (not shown) The engine is pressurized and supercharged.

  At this time, the flow passage area between the vanes 40 and 40 can be arbitrarily adjusted by appropriately rotating the vanes 40.

  When the engine is in a low rotation state, the vane 40 is rotated to the state indicated by the solid line in FIG. 5D, and the throat width W1 between the vanes 40 and 40 is reduced to reduce the opening area. To increase the supercharging efficiency. When the engine is in a high speed state, the choke between the vanes 40 is rotated by rotating the vane 4 to the state of the dotted line in FIG. 5D to widen the throat width W2 between the vanes 40 and 40 to increase the opening area. (Clogging) is prevented.

  As shown in FIG. 5A, the vane 40 has a support shaft 41 in an annular gas flow path 15 formed of a ring-shaped space formed by the shroud 3 provided in the turbine case 10 and the hub 14 of the turbine case 10. , 42 so that the vane 40 can rotate as appropriate. Between the vane 40 blade end surface and the shroud 3 and between the vane 40 blade end surface and the hub 14. It has some clearance (FIG. 4 of Patent Document 1, FIG. 3 and FIG. 5 of Patent Document 2).

JP 2000-8869 A JP 2002-364374 A

  By the way, the flow of the exhaust gas that rotates the turbine impeller 2 through the annular gas passage 15 is a flow along the surface of the vane 40 as indicated by an arrow a in FIGS.

  On the other hand, the flow direction of the gas leaked from the clearance set between the vane 40 blade end surface and the shroud 3 and the hub 14 is as shown by the arrow b in FIGS. 5 (B) and 5 (D). (The axial direction of the support shafts 41 and 42).

  For this reason, the gas leaked from the clearance intersects with the exhaust gas flowing on the surface of the vane 40, the flow of the exhaust gas flowing into the turbine impeller 2 becomes unstable, and the energy of the exhaust gas is effective for the turbine impeller 2 In particular, there is a problem that the efficiency of the turbine decreases at a small flow rate.

  Accordingly, an object of the present invention is to provide a variable nozzle structure for a turbine that does not lower the turbine efficiency.

  In order to solve the above problems, the variable nozzle structure for a turbine according to the present invention is located in the turbine case at a position radially outward of the turbine impeller and spans between a shroud of the turbine case and a hub by a support shaft. A variable nozzle structure for a turbine in which a plurality of vanes formed on the blade are rotatably provided at intervals in the circumferential direction, and a support member that closely contacts at least a part of the blade end surface with the blade end surface on the shroud side of each vane Is provided.

  According to the above configuration, since the support member that is in close contact with at least part of the blade end surface is provided on the blade end surface on the shroud side of the vane, there is no clearance between the part of the vane and the shroud, and the exhaust gas does not flow. Leakage from the shroud side can be reduced.

  Moreover, it is preferable that the support member is a cylindrical body, and the support shaft is eccentrically attached to the cylindrical body.

  According to the said structure, manufacture is easy.

  Moreover, it is preferable to form a recess in the shroud for fitting the support member so as to be rotatable about the support shaft.

  According to the said structure, a vane can be rotated centering on a support shaft with a support member.

  Moreover, it is preferable to provide the said cylindrical body in the upstream of the blade end surface of the said vane.

  According to the above configuration, the exhaust gas does not leak from the shroud side on the upstream side of the vane.

  According to the present invention, turbine efficiency can be prevented from decreasing.

FIG. 1 is a cross-sectional view showing a variable nozzle structure of a turbine according to an embodiment of the present invention. FIG. 2 is an enlarged view of the variable nozzle portion shown in FIG. 1, (A) is a front view, (B) is a side view, and (C) is a perspective view of the variable nozzle. FIGS. 3A and 3B are diagrams showing a state of the variable nozzle in a small opening, FIG. 3A is a side view seen from the hub side, and FIG. 3B is a diagram showing a rotating state of the vane. 4A and 4B are views showing a state of the variable nozzle in a large opening, FIG. 4A is a side view seen from the hub side, and FIG. 4B is a view showing a rotating state of the vane. FIG. 5 is a view showing a variable nozzle portion of a conventional turbine, in which (A) is a cross-sectional view, (B) is an enlarged front view of the variable nozzle portion, and (C) is an enlarged side view of the variable nozzle portion. (D) is a figure which shows the state of the small opening degree of a variable nozzle (a broken line is a state of a large opening degree), and is the side view seen from the hub side.

  A preferred embodiment of the present invention will be described with reference to the accompanying drawings.

  1 to 4 (this embodiment), members having the same functions as those shown in FIG. 5 (conventional example) will be described with the same reference numerals.

  As shown in FIGS. 1 to 4, the turbine section of the supercharger 1 is composed of a turbine case 10 that houses a turbine impeller 2, a variable nozzle 4, and the like. A rotating shaft 20 extending from the turbine impeller 2 is rotatably supported by a bearing case 21 and is not shown at the tip of the rotating shaft 20, but a compressor impeller is coupled, and the turbine impeller 2 and the compressor impeller are integrated. It is designed to rotate.

  A scroll passage 12 for distributing exhaust gas in the circumferential direction is formed in the turbine case 10, and an exhaust port 13 is formed coaxially with the turbine impeller 2.

  Further, the turbine case 10 is formed with an annular hub 14 projecting inward, and provided with a shroud 3 formed along the blade shape of the turbine impeller 2.

  The shroud 3 has a cylindrical portion 30 parallel to the rotation shaft 20 and a flange portion 31 orthogonal to the cylindrical portion 30, and the flange portion 31 is spaced from the hub 14 by a predetermined distance. An annular recess 31 a is formed in the flange portion 31, and an annular support member 32 is fitted into the annular recess 31 a in the same plane as the flange portion 31.

  An annular gas flow path 15 composed of a ring-shaped space is formed by the flange portion 31, the annular support member 32, and the hub 14, and the variable nozzle 4 is disposed in the annular gas flow path 15. The variable nozzle 4 is composed of a large number of vane-shaped vanes 40 that are radially outward of the turbine impeller 2 and arranged at intervals in the circumferential direction.

  As shown in FIGS. 1 and 2, support shafts 41 and 42 for rotating the vane 40 are provided on the vane 40 in parallel with the rotation shaft 20, and the support shaft 41 is rotatable on the hub 14. The support shaft 42 penetrates the annular support member 32 and is rotatably supported by the flange portion 31 (or the annular support member 32) of the shroud 3.

  A feature of the present invention resides in reducing exhaust gas leakage across the vane 40 from the shroud 3 side, particularly at low flow rates.

  In order to realize this, in the present invention, a support member 43 that is in close contact with at least a part of the blade end surface 45 is provided on the blade end surface 45 of the vane 40 on the shroud 3 side. That is, as shown in FIGS. 1 and 2, the vane 40 is provided with a support member 43 such as a cylindrical body in close contact with the blade end surface 45 with respect to the flange portion 31 of the shroud 3. For this reason, in the place where the support member (hereinafter referred to as a cylindrical body) 43 is provided, the clearance between the end surface 43a of the cylindrical body 43 and the blade end surface 45 of the vane 40 is zero.

  The end surface 43a of the cylindrical body 43 has a size such that one end in the radial direction includes the support shaft 42 and the other end in the radial direction substantially coincides with the tip of the vane 40 so as to be provided upstream of the blade end surface 45 of the vane 40. The diameter of the cylindrical body 43 is substantially half of the length of the vane 40 in the longitudinal direction (see FIG. 2). For this reason, the clearance between the vane 40 and the shroud 3 becomes zero, and the exhaust gas does not leak from the shroud 3 side at least upstream of the vane 40.

  The flow rate flowing through the turbine impeller 2 is hub side <shroud side, and the turbine impeller 2 takes out more work on the shroud side. From this, it is considered that the influence of the gas leaked from the clearance of the nozzle on the performance of the turbine impeller 2 is larger on the shroud 3 side.

  Therefore, the present invention provides a cylindrical body 43 in close contact with the blade end surface 45 on the shroud 3 side of the vane 40 and forms a wall on the shroud 3 side of the vane 40, thereby reducing the clearance and reducing the turbine efficiency. The decline is suppressed.

  In order to fit the cylindrical body 43 to the flange portion 31 of the shroud 3, the annular support member 32 is formed with a recess 32a. As will be described later, the recess 32a has an oval cross-sectional shape (oval) so that the cylindrical body 43 can move while rotating around the support shaft 42.

  The support member 43 is preferably a cylindrical body that is easy to manufacture, but is not limited to a cylindrical body, and may be a polygonal column.

  Further, when the cylindrical body 43 having a size covering the entire region of the blade end surface 45 of the vane 40 is provided, it interferes with the blade end surface 45 of the adjacent vane 40, so that the cylindrical body 43 is large enough to cover the upstream side of the blade end surface 45. I am trying.

  The operating mechanism 6 is connected to the protruding end of the support shaft 41 that is rotatably supported by the hub 14, and the operating mechanism 6 is driven by an actuator (not shown) or the like. When the operation mechanism 6 is driven, the support shaft 41 is rotated, and each vane 40 is rotated in conjunction with the support shafts 41 and 42.

  The state where each vane 40 is rotated by the operating mechanism 6 is shown in FIGS.

  The variable nozzle 4 shown in FIG. 3A is a case where the throat width W1 between the vanes 40 is reduced to minimize the opening of the variable nozzle 4, and the variable nozzle 4 shown in FIG. The case where the throat width W2 between the vanes 40 and 40 is widened to maximize the opening of the variable nozzle 4 is shown.

  When changing the variable nozzle 4 from the small opening shown in FIG. 3 (A) to the large opening shown in FIG. 4 (A), or from the large opening shown in FIG. 4 (A) to the small opening shown in FIG. 3 (A). 3B, the cylindrical body 43 moves while rotating counterclockwise or clockwise about the axis 41a of the support shafts 41 and 42 as shown in FIG. 3B or 4B. Thus, the recess 32a has an oval cross-sectional shape (oval) so that the movement of the cylindrical body 43 can be allowed.

  Hereinafter, the operation of the variable nozzle 4 of the supercharger according to the present embodiment will be described.

  Exhaust gas that has flowed into the scroll passage 12 from the outside is accelerated through the annular gas flow path 15 and the variable nozzle 4, flows into the turbine impeller 2, rotates the turbine impeller 2, and is exhausted from the exhaust port 13.

  When the engine speed is low and the exhaust gas flow rate is small, the variable nozzle 4 reduces the throat width W1 between the vanes 40 and 40 to a small opening as shown in FIG. Increase the speed to increase the rotation speed of the turbine impeller 2 and increase the supercharging efficiency.

  At this time, since the cylindrical body 43 that is in close contact with at least a part (upstream side) of the blade end surface 45 is provided on the blade end surface 45 of the vane 40 on the shroud 3 side, the shroud 3 side of the vane 40 is the end surface of the cylindrical body 43. 43a is formed, and a clearance is not formed between the vane 40 on the upstream side of the vane 40 and the shroud 3 side, and exhaust gas may leak from the shroud 3 side on the upstream side of the vane 40. Absent.

  Even if the variable nozzle 4 moves to the hub 14 side due to the pressure balance between the shroud 3 side and the hub 14 side, the cylindrical body 43 that is in close contact with the vane 40 also moves. There is no clearance between the upstream side of the blade end surface 45 of the vane 40 and the end surface 43a of the cylindrical body.

  In particular, in the turbine, when the exhaust gas flow rate is small and the vane 40 has a small opening (the state shown in FIG. 3), the leakage flow of the exhaust gas from the clearance on the shroud 3 side significantly deteriorates the efficiency of the turbine.

  According to the present invention, on the upstream side of the vane 40 on the blade end surface 45, the clearance on the shroud 3 side becomes zero, and the exhaust gas flows as shown by the arrow b in FIGS. 2 (A) and 3 (A). Therefore, the exhaust gas does not cross the vane 40 and is not leaked from the shroud 3 side at least on the upstream side of the vane 40 (arrow). a is the flow along the surface of the vane 40). That is, the flow (arrow a) of the exhaust gas in the vicinity of the throat on the upstream side of the blade tip surface 45 of the vane 40 is not obstructed.

  As described above, according to the present invention, the support member 43 that is in close contact with at least a part of the blade end surface 45 is provided on the blade end surface 45 of the vane 40 on the shroud 3 side, thereby reducing the number of places where the leakage flow occurs. Thus, leakage from the shroud 3 side at the time of a small flow rate can be reduced.

DESCRIPTION OF SYMBOLS 1 Supercharger 2 Turbine impeller 3 Shroud 4 Variable nozzle 6 Operating mechanism 10 Turbine case 12 Scroll passage 13 Exhaust port 14 Hub 15 Annular gas flow path 20 Rotating shaft 30 Cylindrical part 31 Flange part 31a Annular recessed part 32 Annular support member 32a Recessed part 40 Vane 41, 42 Support shaft 43 Support member (cylindrical body)
43a End face 45 Blade end face

Claims (4)

A vane formed in the turbine case so as to span between the shroud of the turbine case and the hub is supported by a support shaft so as to be spaced apart in the circumferential direction. A variable nozzle structure of a turbine provided with a plurality,
A variable nozzle structure for a turbine, wherein a support member that is in close contact with at least part of the blade end surface is provided on a blade end surface on the shroud side of each vane.   The variable nozzle structure for a turbine according to claim 1, wherein the support member is a cylindrical body, and the support shaft is eccentrically attached to the cylindrical body.   3. The variable nozzle structure for a turbine according to claim 1, wherein a recess is formed in the shroud to fit the support member so as to be rotatable about the support shaft.   The variable nozzle structure for a turbine according to claim 2 or 3, wherein the cylindrical body is provided on an upstream side of a blade end surface of the vane.

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